Products for converting alternating current (AC) to direct current (DC) are commonly found in the marketplace today. These products, when used to move electrical energy into a battery, are referred to as chargers. Products that convert DC into AC are referred to as inverters.
Hybrid-Electric Vehicles or “HEV”'s have both an electric drive train and a gasoline or other form of combustion engine. While various specific HEV configurations are possible, generally speaking, the electric motor may drive the vehicle, drawing energy from a battery pack alone or in combination with the combustion engine may also power a generator that charges the battery pack. One problem with many existing mass produced HEVs is that the full potential of the hybrid drive system is not realized due to the limited amount of on-board electrical energy storage. This problem is addressed by increasing the energy storage capacity of the vehicle to allow greater use of electricity in place of gasoline, which is being facilitated by technical advances in battery or other energy storage forms, among other things. Higher capacity energy storage systems facilitate charging from an external supply to offset and reduce petroleum fuel consumption that would otherwise be required by the petroleum fueled engine. Such a configuration is known as a Plug-in Hybrid Electric Vehicle or PHEV.
Now consider that PHEVs often now have a large capacity battery for electrical energy storage but that stored energy is used only when the vehicle is moving. When the vehicle is at rest the battery system is idle and underutilized. It has been recognized that the energy storage capacity of PHEVs could be utilized to store electrical energy when the power is available and it could be called upon to supply electrical energy when required during times of peak electric grid demand—a concept referred to as Vehicle-To-Grid or V2G.